The text says in formal letters the 'to' address should be positioned below the 'from' address, but the picture show that they overlap and the 'to' address starting half way down the 'from' address.
Is there a set difference between the first lines, or what?
Normally you will put your address (the "from" address) in the top right hand corner of the page. The address to which you are writing (the "to" address) is one line down and on the left hand margin of the page.
I am not sure what you mean by "a set difference between the first lines".